This Unit provides a nucleus of ongoing inquiry where investigators can benefit from their mutual association and be available to exploit research opportunities in psychiatric epidemiology. The integration of the Field Stations into their communities makes available laboratory populations in which to measure rates of mental disorders and to explore their modifiable social concomitants. It is proposed to survey, as a form of epidemic intelligence, the distribution and nature of depression and the relationship of stress to episodes of psychiatric care. Maintaining a psychiatric register allows the analysis of service patterns and the evaluation of their effectiveness especially in regard to the changing incidence of long-term psychiatric hospitalization. The social breakdown syndrome concept has been developed and quantified as a criterial measure of the results of new patterns of mental health care. It is now possible to investigate reliably further aspects of its causes and prevention. Toward these goals, new methods for estimating incidence and episode duration have been initiated and will be developed. A new system to retrieve data from the published literature is used in a continuing effort to help the researchers keep abreast of the new and important developments in psychiatric epidemiology.